Sink-float apparatus for separating solids



, 1949. c. Y. GARBER ET AL 5,

FLOAT APPARATUS FOR SEPARATING SOLIDS arh 22 SINK- 2 Sheets-Shet 1 Filed 00%,. 17, 1944 FRANK M. McKINLEY CLAUDE Y. GARBER Smaentor attorney March 22, 1949. c. Y. GARBER ET AL 2,455,220

SINK-FLOAT APPARATUS FOR SEPARATING SOLIDS 2 Sheets-Sheet 2 Filed Oct. 17, 1944 FRANK M. McKINLEY CLAUDE Y. GARBER Zmnentor Patented Mar. 22, 1949 UNITED STATES TENT OFFICE SIN K-F-LOAT APPARATUS FOR SEPARATIN'G, SOLID S2 Claude Y. Garber and Frank M. McKinley, Kellogg, Idaho, assignors to The Sink & Float 'Corporation, New York, N LY a corporation Application October-17, 1944, Serial No. 559,089

2 Claims. 1

This invention relates to asink-float apparatus for separating solids, useful in the separation of solid materialsof different specific gravities, and, more particularly, is themethodand apparatus for use in mineral recovery fields, (whereby valuable materials oflknown specific gravity may be separated from waste materials of lighter or .different specific gravity in a medium of controlled specific gravity.

In recent years the oldermethods of gravity to xthe-surfaceof the medium are removed while the particles of higherspecific gravities sink to the bottom of the medium-containing-tank-and are removed by drags, elevators or by other means. separately from the medium; The application of this principle to ore recovery depends upon the fact that the specific gravities of the valuable mineralsto'be recovered generally difiersmateriallyfrom-the specific gravi-ties of-thematerial commonly known las gangue' which is tobe dis-- carded, the latter havingia different but generally lower specific gravity than the former.

It is extremely important that separation take place in aquiescent pool of medium, since heavy I currents in the medium are bound to interfere to a certain degree with the accuracy of the specific gravity separation taking place; One of the prime criticismsof the earlier methods andfmechanisms is:.that: ther-e have :been adverse? currents in the medium pool which tend to preventfloating of that portio'nof the feed material having aspecific gravity below that'of the medium; contamination of the sink material; or there areparticles of .a border-line specific gravity entrapped in the medium pool which contaminate the medium and interfere with effective-separation.

The'speedat which separation of the sink from the float particles takes .place depends upon the. weight of the individual particlesrand also on the diiference in specific 'gra-vities between the vari ous particlesand the medium. Thus, the large and heavy particles sink fast and separation of these' 'efrom the-float 'is easily achieved; While Thus two types of particles are removed smaller particles or those with a lower specific gravity than the medium (commonly known as particles of marginal density) are not so readily separated.

In the past another of the difficulties has arisen due .to the fact that there is a Water film on the surface of the bodyof medium and consequently a zone .of light specific gravity near the surface.

Thiscondition is partly due to the squeezing of the moisture oil the feed, which moistureremains on the surface of the medium when the feed is at that point, and tends to prevent the rise of the float to a point where it may be easily skimmed. This condition .has only beenrovere come by resorting to heavy currents induced to. travel through the medium body and, in effect,'.

force floating. Such currents are undesirableas they reject as float .border-linesink particles. I We have here a prime criticism of the prior art. In addition to this question. of suspension, the surface dilution produces undesirable settling of .the float and medium solids.

We have found another disadvantage in the prior art where as is customary, the operators have introduced the feed material in the medium pool at its surface to'one side. feed produces unusual conditions in that the feed,

which will eventually separate as float, is immediatelybuoyed, but the sink, and particularly those afiects thetime factor and has resulted in overa size machines iorthe volume of separation thatis produced Having in mind these, and other defects of the prior art, it is a prime object of this invention .to provide a method and means for introducing feed material and medium in a sink-float operation andstill prevent adverse current formation.

A still further object of the invention is the provision, in a sink-float method, of a process of removing the fioat, while avoiding undue agitation of the medium body or current formation.

One other object of our invention is the provision of a mechanical structure which is'simple to-construct and operate and which will practice our method of sink-float separation.

The foregoing objects and others ancillary thereto, we prefer'to accomplish as'follows:

According, to a preferred-embodiment of our solids in a liquid, to which body is fed granular- This manner of materials of different specific gravities at a point below the surface of the body of medium, in what may be referred to as an intermediate zone of separation. The separation phenomena takes place so that portion of the feed having a specific gravity less than that of the medium, floats to the surface, and the remainder which has a specific gravity greater than the medium, sinks below this zone of separation. The float is skimmed from the surface and the sink may be elevated from its lower positioning in the pool to an overflow lip, and thereafter, is disposed of in any of several conventional ways. We have found that it is important in skimming the float from the surface of the body of medium that the same be done intermittently but, most importantly, with a sweeping motion completely across the pool to a border thereof, at which point is located an over-flow lip for the float. One practical mode of accomplishing this method is an apparatus comprising a trough having an open bottom and forming a sink-float chamber. This trough is enclosed by a V-shaped tank which has a. sump below the open bottom of the trough for the collection of the sink material. Means is employed for directing sink material into said trough at what is the approximate mid-portion of the pool of medium contained therein. Conduit means is also provided for conducting medium to said tank below its surface. We have found that our method is practiced with facility and that the operation of our mechanism is improved by introducing a certain portion of the feed of medium coincidental with, and through the same means, as is employed for feeding the granular material which is to be separated. A desirable form of tank is one which is V-shaped so that the sink is concentrated easily for engagement by the elevating or sink-removing mechanism, which we show to have a form of a paddle dra which travels down one inside inclined wall of the tank through the lower sink accumulating portion thereof, and up the opposite wall to an overflow lip and thence outward for disposal. The surface of the pool is skimmed of float by means of an endless paddle drag arrangement preferably operating at right angles to the mechanism used for removing sink, which skimming mechanism will sweep completely across the pool, blade after blade, in such a manner that there is only a minimum of surface agitation created. Suitable conveyors and conductors are used for delivery of feed material and the medium to the mechanism and a more or less conventional type of launder and tailing screen is employed for the separation of medium from either the sink or float as it leaves the machine for the recovery of such medium that may be escaping the machine in that manner.

The novel features that we consider characteristic of our invention are set forth with particularity in the appended claims The invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, in which:

Figure 1 is a vertical sectional view taken longitudinally through our sink-float machine along the plane suggested by line ll, of Figure 2;

Figure 2 is a vertical sectional view taken transversely through our sink-float machine along the plane and looking in the direction suggested by the arrows 2-2 of Figure 1;

Figure 3 is a vertical sectional view in perspective of the tank and trough of our sink-float machine; and

Figure 4 is a fragmentary perspective view of a modified sub-surface medium inlet slot arrangement.

A sink-float machine to practice our process, and to overcome the defects hereinbefore enumerated, must have at least two totally distinct characteristics; it must be capable of being constructed and operated easily in order that unduly great skill is not required in its production or operation; and it must have a high output in comparison with the power input, to the end that greatest milling economy may be obtained. Accordingly, a preferred embodiment of our invention, referring to the figures of the drawing, is constituted by a tank into which is placed a trough defining a zone of separation, and to which is delivered medium and granular feed material in a mid-portion of the zone of separation; and on which tank is mounted float skimming means and sink removing and elevating means. Upon a. suitable frame F is mounted a V-shaped tank l0, having a lower rounded bottom portion l2. By means of conduit l4 medium is fed into the side of the tank through opening 16 to the pool contained by the tank. This delivery is substantially below the pools surface. Alternatively medium may be introduced through conduit to header 82 from which it passes through slot 84 in tank ID in broad distribution with low velocity to avoid boiling tendencies sometimes resulting from entry in high velocity concentrated streams. The ends ll, [3 of the tank join the edges of Walls ID to make the tank watertight. Disposed between the ends of the tank parallel to and in spaced apart relation to the side walls thereof are the trough walls [8, whose bottom edges are unattached to form an open trough. Rising above the walls, in vertical relation thereto, are the septums 20, 20 which attach to structural members 2| that serve as supports for the float skimming mechanism.

The float-skimming mechanism comprises a pair of shafts 22, 24, suitably bearinged upon the member 21, each having sprockets 23, 25 over which pass the endless chains 26 that carry a plurality of skimming blades 28. Sprockets 23 are rotated by means of power applied to belt 30 which rotates counter shaft 3|, to in turn empower belt 32 which is mechanically coupled by a conventional sheave to the shaft 22. A motor not shown is used to motivate the belt 30.

The sink-removing mechanism comprises shafts 4'0, 42 and 44 placed adjacent the corners of the tank. Each shaft has thereon respectively pairs of sprockets 4|, 43 and 45. Shaft 42 is powered by belt 46 which receives power from the reducer unit 48 to which rotary motion is supplied by motor 50 shown in Figure 1.

About the sprockets 4|, 43 and 45 is threaded the endless chain 52 that has a plurality ofpaddles 54' traveling in the direction indicated by the arrow in Figure 2. It will be seen that these paddles descend on one wall of the tank (that to the right in Figure 2) sweep the narrow rounded bottom I2 of the tank to remove the sink therefrom and elevate the same upward to a point where it is deposited outside of the machine across the over-flow 56. The sink material, which may run in size from /64 or less to as great as three inch particles, falls upon the screen 58 and passes over the same for any suitable disposal. The medium carried over lip 56 ieaves the sink" and descends 'throughscreen 58 into the launder 60 from which it is conveyed by conduit means for'treatment or return to the machine.

The float materialwhich is skimmed from the machine--in this embodiment at right angles to the:direction of movement of the sink-passes outwardly over the lip 29 on the upper edgeof end wall I3 and thence to the screen 3t and the lip 33. The medium which may escape the machine with the float leaves the float and descends through screen -35 into the launder 35 which converges to conduit (by which this medium material is returned to the machine or processed 'as desired.

By utilizing a conveyorlfl, the feed of granular material is delivered to the hopper 12 from -whenceit passes into the conduit 7d and the *feedchute'lfi for deposit interior-1y of the trough formed by walls I 8, at approximately a vertical mid-portion of the separating zone. In addition to thefeed of medium through the conduits l4 and openings l6, medium may also, and preferably, be introduced into the machine through the conduit M and trough it. For this purpose medium conduit nozzle 18 is employed to discharge its fluid contents into the incoming stream of feed material descending from the conveyor It.

By reason of this construction, there is a zone of separation approximately in the middle of the tank vertically and to this zone the feeding takes place. There are several important advantages gained by this arrangement. For example, the medium is less disturbed, since there is virtually no turbulence at the point of entry of the feed or at th surface, as was customary in the prior art. Also there are no adverse currents created within the mechanism, especially within the pool of fluid medium, so that there are only two directions in which the particles being fed will move, one being the natural rise of the float and the other being the travel of the sink as it falls to the lower portion of the tank. Such medium as rises to replace that being removed by the skimming operation over the float discharge lip, is of a small amount so that no adverse current condition arises.

By reason of this mechanism, and this methd of feeding granular material, the specific gravity of the medium, and especially of the zone of separation, is easily maintained, at the proper predetermined point, due to the fact that the moisture adhering to the feed is so diffused in the medium being admitted with the feed that dilution does not take place. Thus it is possible for operators, knowing the moisture content of their feed, the specific gravity of the medium being added with the feed, to at all times maintain without difficulty the optimum predetermined specific gravity for the particular separation. This is to be distinguished from the prior art conventional feeding wherein there was a water film on the surface of the body of the medium and consequently a zone of low specific gravity near the surface.

Because in our mechanism separation takes place rapidly and directly upon the introduction of feed material, the time for separation is shorter than was previously possible, consequently a machine according to our invention has a much higher production than would a machine of similar size built according to the prior art teachings. To put it another way, it is possible to accomplish a given quantity of separation with: a smaller-mechanism :according to 1 our invention.

"By reason, of 30111 method of skimming'z-the float, aslherein .disclosed we .are able, to. reduce to the'absolute minimum. the. surfaceagitation ,When a @float particle reaches the sursub-surface currents or become so mingled with descending'sink 3,5170 finally-be. removed thereby .andrcontaminatathe sink. Note; also that thereis very. slightattritionof the float particles 1 and:consequently,; a. reduction. of the amount. of fines that might bezproduced.

I Thegmannerginrwhichwe. feed the medium. .to

1- thegpool" by means of; the. conduit hi-and. trough 7.6 eliminates "boiling, turbulence or adverse cur- .rents' in thetseparatingr zone; since the flow .of

medium is in the form of a thin sheet moving smoothly with the particle feed and is distributed over a fairly wide area. We employ both this method of feeding and the sub-surface feeding through the openings [6 as medium controlling means, so that there is constantly being supplied an amount of medium equal to that being removed with the float and sink, to the end that all heavy or adverse currents in the separating zone are eliminated. It is to be noted, however, that there is one distinct current created at the lower edges of the trough walls I8, [8 to act upon the sink as it is leaving the separating zone. This last current is important in that it assists the lifting of the float and enhances the descent of the sink. By the use of these two methods of feeding medium, it is possible when circumstances require, to establish controlled downcurrents or up-currents whenever necessary.

It is to be noted that the introduction of feed material is asymmetrically located in the cell lengthwise. By thus introducing feed material at one end of the cell a certain amount of classification of the sink can be produced, since the heaviest fraction of the sink will report to the sink removal mechanism directly under chute l6 and, when the sink is raised to the overflow lip 56 the heaviest fraction can be separated from that which has settled farther from the trough 76, at which point will report that fraction having a lesser size or density. It has been found from actual operation that such middlings as may be introduced with the feed or as may escape from the float at or near the float discharge lip 29, will descend to the sink removal mechanism at that end of the tank farthest from the location of the feed trough 16, and, when elevated, these middlings can be cut out of the sink overflow portions and be disposed of as desired.

Having thus described our invention, we claim:

1. A sink-float machine for treating granular materials of different specific gravities, comprising: an elongated tank of V-shape, a pair of upright walls extending in said tank between the ends thereof from near the upper portion to substantially near the bottom and forming an openbottom trough defining a separation area in the tank, a chute in one end of said tank having discharge lip medially located vertical of said trough between the walls thereof, means for conveying granular material to said chute, means for delivering medium to said tank below the surface of a medium pool established therein, an endless drag skimming mechanism operable solely over said separation area and the upper portion of said trough above the level of said discharge lip, and endless means operable in said tank exterior of said trough for removing sink from therebelow.

2. A sink float machine, for separating granular materials of difierent specific gravities, comprising: an elongated tank of V-shape having a discharge lip at the top of one side edge, a pair of upright partition walls spaced inward from the side walls of said tank and extending from end to end of the tank, said tank having a discharge lip on one of said ends, said tank having an inlet chute for the granular materials at the other end thereof and an opening from said chute between said partition walls, the opening having its top edge below the tops of said walls and its bottom edge above the lower edges of said partition walls, an endless drag skimmer operable along the top of said partition walls toward the end lip, and a sink removing conveyor extending to the bottom of the tank outside of said partition walls.

CLAUDE Y. GARBER. FRANK M. MCKINLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 873,951 Langerfeld Dec. 17, 1907 1,290,515 Conklin Jan. 7, 1919 1,681,627 Sawyer Aug. 21, 1928 2,108,290 Levin Feb. 19, 1938 2,139,047 Tromp Dec. 6, 1938 2,150,917 Foulke Mar. 21, 1939 2,191,805 Pearson Feb. 27, 1940 2,203,601 Rakowsky June 4, 1940 2,209,618 Vogel July 30, 1940 2,315,536 McNeill Apr. 6, 1943 2,362,482 Haworth Nov. 14, 1944 

